The WFI N2 Flushing System There is a solenoid valve mounted on the telescope base at the low pressure side of the N2 gas supply. This valve is driven by the TCS VME computer under the supervision of a program task plus a set of commands that can be issued from the vxte2p2 console (or from any console using an rlogin) for; opening the valve, closing the valve, reading the status, and switching the system to automatic and manual modes.

The commands are the following five:

• N2_status


• N2_mode_manual


• N2_mode_automatic
  • Checks if the system is in manual or automatic mode.
  • If in manual mode; send the above mentioned warning message to the console every 5 seconds.
  • If in automatic mode; read the humidity every 2 seconds, average 150 values and open the valve if the humidity average is >= 60% and close the valve if the humidity average is <= 50%.


• N2_open


• N2_close

Note1: Always at boot time the conditions by default are the following:

• System mode in automatic.
• <=50% closing and >=60% opening.

Note2: After boot it is possible, if desired, to change the opening and closing points just by changing the globals, "double N2cls = X.X" and "double N2opn = X.X" to any value between 0.0 to 100.0.